1. Field of the Invention
The present invention relates to an ultrasonic endoscope that is inserted into a coelom or other body cavity to conduct an endoscopy and an ultrasonic examination.
2. Description of the Related Art
Generally, an ultrasonic endoscope is so designed that an endoscopic observation unit, constituted by a lighting portion and an observation portion, and an ultrasonic test unit, which includes an ultrasonic transducer, are provided at the distal end of an insertion portion to be inserted in to a coelom. A coelom examination is performed by introducing the insertion portion into the coelom and using the endoscopic observation unit. Then, if during the endoscopy an abnormality is observed, additional information concerning the state of the body tissue can be obtained using the ultrasonic test unit. Further, by taking into account all the results produced by the endoscopy and the ultrasonic examination, therapeutic treatment or the sampling of tissue can be performed using treatment equipments, as indicated. The treatment equipments used with the ultrasonic endoscope can not only be those such as forceps and high-frequency treatment equipments, which can be used with the endoscope, but also puncture treatment equipments provided with puncture needles that are manipulated and guided by using the ultrasonic test unit. Therefore, in an ultrasonic endoscope, a treatment equipment insertion channel is formed that will accept and guide a variety of treatment equipments.
For the insertion portion of the ultrasonic endoscope, an elevation operating section is connected to the distal hard portion to which the endoscopic observation unit and the ultrasonic test unit are to be attached, so that the distal hard portion can be pointed in a desired direction, and the flexible portion of the insertion portion is coupled to the elevation operating section. Further, the base end of this flexible portion is connected to the main control portion, which an operator holds and manipulates. That is, an angle control device is provided for the main control portion to permit the elevation operating section to turn the hard distal portion. Also, a treatment equipment introduction portion for inserting a treatment equipment is provided for the main control portion. In addition to these operations, the cleaning of an observation window and a suction operation are also performed by the main control portion, and in order to perform these various operations, switches and buttons are provided for the main control portion. Further, a connection cord extended from the main control portion is branched en route and is detachably connected to a light source, a processor and an ultrasonic observation apparatus.
As is described above, the endoscopic observation unit and the ultrasonic test unit are attached to the distal hard portion of the insertion portion, and the treatment equipment insertion channel is opened. The ultrasonic test unit is located nearer the distal hard portion, the endoscopic observation unit is located nearer the base end, and the treatment equipment insertion channel is located between the ultrasonic test unit and the endoscopic observation unit. Generally, as a common ultrasonic endoscope, an ultrasonic transducer is constituted by arranging multiple ultrasonic oscillators to perform electronic scanning. The ultrasonic oscillators are arranged from the end of the hard distal portion to the base end, and two types of arrangement are used: an arrangement on a single plane and an arrangement having a convex shape. In order to broaden the ultrasonographic view field, the ultrasonic oscillators are closely arranged and have a convex shape, so that electronic convex scanning can be performed.
As is described above, the ultrasonic oscillators constituting the ultrasonic transducer are attached to the end of the hard distal portion, and the endoscopic observation unit is attached to the base end. With this arrangement, the view field of the endoscopic observation unit must be obtained, and also, a treatment equipment inserted through the treatment equipment insertion channel must be constantly captured in this view field. Further, when a puncture treatment equipment is employed, at the stage before the puncture treatment equipment is inserted into body tissue, manipulation of the equipment is supervised by using the view field of the endoscopic observation unit. At the stage following the insertion of the puncture treatment equipment into the body tissue, manipulation of the equipment is observed using the ultrasonic test unit. While taking the above description into account, the opening of the treatment equipment insertion channel must be located between the attachment portion of the ultrasonic test unit and the attachment portion of the endoscopic observation unit. Further, the center of the viewing field for the ultrasonic test unit and the center of the viewing field for the endoscopic observation unit must be arranged in parallel, or must cross at a shallow angle, and the ranges of the viewing fields must overlap, to a degree.
Therefore, the endoscopic observation unit constituted by the lighting portion and the observation portion is located nearer the base end, separated from the position whereat the treatment equipment insertion channel is opened, and is attached to the inclined face of the hard distal portion. Further, in order to improve the operation of a treatment equipment, an elevator provided for the opening of the treatment equipment insertion channel is employed to control the derivation direction in which the treatment equipment is guided. An ultrasonic endoscope that is thus arranged is described, for example, in JP-A-5-344973.
When, as is described above, the elevator used for a treatment equipment is attached to the hard distal portion, in addition to the ultrasonic test unit and the endoscopic observation unit, the structure of the hard distal portion becomes extremely complicated, and depending on how the components are arranged, the diameter of the hard distal portion will be increased. Especially since the elevator used for a treatment equipment is to be remotely controlled by the operating unit of the main body, the elevator must comprise: a treatment equipment guide for guiding the treatment equipment so that the angle can be adjusted; and an elevation operating unit for remotely changing the angle of the treatment equipment guide. Thus, the treatment equipment guide is located nearer the distal end than the opening of the treatment equipment insertion channel, and the elevation operating unit, for remotely controlling the elevation of the treatment equipment guide, is located alongside the treatment equipment guide.
In order to increase the resolution of an ultrasonic image that is obtained by the ultrasonic test unit to represent tomographic information of body tissue, the number of ultrasonic oscillators constituting the ultrasonic transducer must be increased. Wires are connected to the individual ultrasonic oscillators, and the portion whereat the wires are inserted is formed at the lower portion, whereat the elevator is attached. As the number of ultrasonic oscillators is increased, so too is the number of wires, and the portion in cross section that the wire insertion portion occupies is accordingly increased. In addition, since the endoscopic observation unit must be located forward of the portion whereat the elevator is attached, the object optical system constituting the observation unit is located above the elevator, and the light guide constituting the lighting portion is located on either side or both sides of the elevator. Therefore, unless these components are arranged logically, the diameter of the hard distal portion can not be reduced.
Since the hard distal portion is coupled with the angle portion so as to be separable, by separating the distal end from the angle portion, maintenance, such as the repair or inspection of members mounted inside the insertion portion, and the replacement of parts can be performed. The ultrasonic transducer, which is attached to the end of the hard distal portion, can be separated by pulling it forward from the hard distal portion.
As the lighting portion and the observation portion that constitute the endoscopic observation unit can not be pulled forward, to perform maintenance, these components are pulled backward from the base end of the hard distal portion. An enormous number of wires extending from the ultrasonic transducer are led from the hard distal portion to the angle portion, and the elevator is located at the hard distal portion. Thus, during the operation performed to remove the constituents of the endoscopic observation unit from the hard distal portion, the enormous number of wires constitutes an obstacle that can interrupt the removal of a member to be repaired, and can result in the breaking of wires. Furthermore, since the treatment equipment insertion channel and the operation wire for elevating the treatment equipment guide are also led to the angle portion, separating the light guide constituting the lighting portion, the object optical system constituting the observation unit, and the solid-state imaging device from the hard distal portion is also extremely difficult. Further, when these components are attached to or detached from the hard distal portion, an inconvenient event, such as damage to another member, may occur. Moreover, since when the elevator for the treatment equipment is to be separated and repaired it must be pulled backward from the base end of the hard distal portion, the same problem will be encountered.